Amisit Magicae
by Crystia
Summary: Merlin is offered a trade: his magic for Arthur's life.
1. Chapter 1

**AU. Merlin reaches the crystal of Neahtid before Morgana can steal it.**

**Re-write of "The Witch's Quickening" (s2 ep11) and onwards.**

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ooo

The bowels of the castle were dark and dank, causing sporadic shivers to run down Merlin's spine. It was far too cold to linger underground, but it seemed evil sorcerers cared little for the health of frozen manservants. If Merlin ever tried to overthrow the crown, he thought with a scowl, he swore to limit himself to midsummer plots.

Alas, Alvarr did not share his sentiment. Merlin had overheard the man pleading with Morgana to steal the Crystal of Neahtid, and while he shied from the thought of her betrayal, he admitted the man spoke well. The soft, persuasive voice might have seduced Merlin, except for his faith that Arthur, not a crusade for revenge, would save magic. Merlin feared that combined with Mordred's appeal, Morgana might think she'd taken the righteous path. She always wanted justice and vengeance; with her newfound powers, she might be misled. The dragon warned him as such regularly.

"_Aliese_," he whispered when he reached the proper room. The door unlocked with more of a thud than a click, but he startled more at the soft flash of gold that briefly lit the wood. The eerie yellow didn't quite match the flame of his torch; his eyes glowed with a harsher shade when he used magic.

He suppressed a shiver and slipped inside the room cautiously, the air growing impossibly colder, his first breath creating a huff of mist. Catching his first glimpse of the crystal, he hesitated. Gaius had warned him not to approach it, explaining that the crystal showed futures that drove men mad, but the power called to him. Like attracted like, and Merlin's magic swirled chaotically in response to the crystal's power. He had never been in the presence of something so potent; the dragon was strong, but he was stronger. The crystal surpassed even himself.

Closer and closer he went, until he stared directly into its depths, and screamed.

Future and past, present and alternative presents, possible and true and _oh-_ it hurt. Gaius was right, anyone else _would_ have gone insane, but Merlin's magic protected him from the worst. The connection snapped in an instant, as quickly as it formed, and Merlin stumbled back with a gasp, trembling violently. Only one vision remained with him, but its intensity had burned an irremovable impression on Merlin's mind, and he swore that he must find a way to prevent it. Except he couldn't.

Arthur _would_ die by Mordred's hands. It was written.

But it turned out that Time was not so hasty to deny a plea from Magic.

"We can save the king from his bane and magical foes," the crystal whispered. Its voice was multifaceted and unnatural, coming from everywhere and nowhere at once. "We can offer him protection beyond your magic, confined as it is to your human form. But we require a sacrifice for such a selfish request. Defying fate is not impossible, but it is not easy."

Of course Merlin agreed. He'd already dedicated his life, his magic, and his soul to the prince, Albion, and the salvation of magic. Again and again he'd gambled with his life. He agreed blindly to the offer, desperately, not even asking the price.

"Anything," he said, and meant it.

For a fate so entrenched in prophecy as Merlin's and Arthur's, he found out, the price Time asked for proved far more devastating than his life.

Sacrificing his magic felt like dogs tearing him limb from limb, slowly and deliberately. It felt like death cruelly abandoning him, leaving him to suffer, as he bled every drop of blood in his body. It felt like fire, and he could only watch his disembodied corpse burn, and he could feel it burn. Oh, he could feel it. His soul wept; he screamed until he coughed blood, and then he gurgled. He was Magic. Or he had been. Without it, what was he?

He didn't know how long he suffered until he collapsed, and he he didn't know how long he laid on the floor, aching, empty, and unwilling to move. He might have taken a dagger and finished the job, ended the pain, except his body wouldn't obey his commands, only giving an occasional spasm and flare of agony.

Morgana found him. So Alvarr had convinced her to steal the Crystal of Neahtid, after all. Despite the dragon's warnings of her imminent betrayal, Merlin couldn't quite see her as evil. Sometimes he caught a glimpse of how she might fall, but she tried so hard to achieve justice. She defied King Uther and saved young druid boys, displaying more bravery than Merlin had ever done.

He wanted to save her, but after visiting the druids, Merlin knew she now feared Uther far more than her magic, and fear turned so easily to hatred.

He'd failed to help her, but at least he'd saved Arthur, even if his efforts went unknown and he thought this with his dying breath.

"Merlin?" she exclaimed, shocked and horrified by the sight of his motionless form. "Merlin," she said again, panicked this time. Trembling fingers checked his neck for a pulse, but whether she found one or not didn't matter to him. His eyelids fluttered, and he spasmed at her touch.

He heard her urgently calling for the guards as he passed out. His last thought was a vague hope that when Arthur found a manservant to replace him, he chose one who would step on a prince's boots rather than lick them.

ooo

Merlin awoke to the sound of pacing. He stared blankly at the ceiling for a long moment, detachedly recognizing it as Gaius's quarters. Pain pulsed throughout his body, but that too felt distant.

The pacing turned out to be Arthur. The steps stuttered to a halt; the prince had seen him awaken. Merlin wished he hadn't.

"Merlin," Arthur exclaimed. "You're awake!"

Merlin turned his head, ignoring the way his neck throbbed angrily. For the briefest, briefest of seconds, the sight of Arthur made him forget the loss of his magic, his mind automatically searching for a witty retort, insubordinate and blasé. Very observant, sire. There's no fooling you.

Then the emptiness returned, with the pain twofold. Insidious, disparaging whispers told him that he'd outlived his purpose. He'd saved Arthur; he could do little more good without magic. His power remained the only reason Merlin had befriended Arthur in the first place. It had given him the courage to speak against a noble's bullying and the opportunity to work as his manservant. Without his magic, he doubted he could so much as finish Arthur's lists of chores. The prince had said so many times that Merlin had no redeeming skills, and now he was right.

Arthur faltered at the lack of response, but recovered soon enough. Merlin had just woken up, after all; the prince likely tributed his silence to grogginess and pain.

"Does anything hurt? Gaius is out. I volunteered to watch you while he fetched some medicine," Arthur said, crossing his arms. "Lucky I did. I get to be the first to tell you how utterly _stupid_ you were."

Sitting in a chair near the foot of the bed, he crossed his arms and waited a beat, but Merlin said nothing. A sense of unreality blurred the world, as if dulled without his magic to sharpen it.

"You don't deny it, then," Arthur said, this time eying him with a raised eyebrow, for a Merlin without anything to say was unfeasible. A Merlin without his magic would have been equally so, a few days ago. "Morgana told me you went to her about rumors you heard in town, something about a magical crystal being stolen."

His mind apathetically turned over Arthur's words. Morgana had lied to protect them both, it seemed. Wishing distantly that she'd just sent him to the pyre and been done with it, he returned his gaze to the ceiling, turning his head with enormous effort. He wondered if his magic had helped him move and carry himself, since right now he felt like he had a hollow body with a heavy iron shell. At least, for the moment, the world seemed comfortably far away and untouchable, an unsolvable problem with which he need not concern himself.

Then Arthur spoke, dragging him back. He unwillingly listened.

"Why didn't you come to me instead?" Arthur demanded, clenching his fists and gazing at him intently. Merlin could still see him from the corner of his eye. "Why Morgana? I could have helped and brought guards. What made you think _you_ could do anything?"

Closing his eyes, Merlin could reticently admire the irony of the situation. Forever safe from Arthur's discovery of his magic he might be, but he would receive no recognition for any of his heroics or his last, excruciating sacrifice, the most painful of them all. He was now exactly as useless as Arthur claimed.

"Why aren't you saying anything?" Arthur snapped, losing his patience at last. "Are you deaf as well as dumb?"

A pause. The prince grew noticeably angrier, and Merlin decided it might be more trouble to leave him be than to give an answer.

"No, sire," he managed at last, a dull, blank rasp. It didn't come easily, given his haze and damaged throat. In fact, he focused so completely on forcing out the words that he didn't immediately recognize Arthur's insult. The prince might not have noticed, either, except for the contrast between their first interaction and their current one. Arthur gave a visible double-take.

"You-" the prince started with irritation, then deflated. He looked down, tugging at his gloves. "Are you all right, Merlin?

Another pause. Merlin had lied to his prince countless times before, yet he thought this one might be the heaviest lie of all, because it might be the very last one he had to tell for his magic. Once he would have been relieved, but this lie was his last for all the wrong reasons.

"I'm fine, sire."

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ooo

**A/N: Thanks for reading! Umm. Feedback would be very much appreciated, if you can spare a few seconds. :)  
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	2. Chapter 2

**If anyone was wondering, I changed the title. I can't do titles. What are titles.  
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ooo

Merlin fell asleep some time during Arthur's attempts to draw him into conversation. The prince managed to keep his temper after his first lapse, so Merlin let himself drift away. As he dozed, he thought Arthur appeared to grow more and more agitated; he concluded that Gaius was running late. A prince had more important duties to attend than visiting idiotic manservants, but since Merlin did not, he slept. Candles lit the room the next time he awoke, and Gaius stood nearby, finishing the last of his potions before turning in for the night. Merlin shifted, aching, and Gaius glanced up.

"Merlin, you had us all worried," the physician greeted, smiling with genuine concern and affection. Merlin couldn't bring himself to smile back. "I have some medicine you should take, now that you're conscious. Prince Arthur forgot to give it to you when you awoke earlier, he seemed rather anxious-"

"It's gone," he said, because he thought Gaius's fussing might shatter him. He couldn't bear the man's relief and joy when he knew they were short-lived. Selfish of him, maybe, but he wanted consolation that Arthur would never give.

"What's gone?" Gaius furrowed his eyebrow in confusion. "The crystal? I take it Alzarr succeeded."

"No," Merlin choked, because he knew he had to say it, but he couldn't get the words out. He wondered briefly if saying it aloud would finalize his loss.

"Merlin?"

"My magic," he whispered, and he heard a sharp intake of breath from the doorway. Gaius's eyes widened, and when the man turned around, Merlin could see Morgana standing on the threshold.

"Lady Morgana," Gaius said tremulously. "I'm afraid Merlin is still a delirious from his fever. Magic has a way of making its victims speak untruths. His proximity with the crystal was too much for him; I think it might be best if visitors waited until tomorrow. If you give me a moment, I'll have the potion for your nightmares ready-"

"It's all right, Gaius," Morgana said, shaken but firm. "Merlin?"

Merlin closed his eyes. He would be sent to the pyre despite the loss of his magic. He'd scream as his skin curled away from bone and choke on the smoke created by his own burning flesh. Arthur would know the truth, and Merlin would not even have the option of saving himself. Dread mingled with resignation; he didn't much fancy burning alive, but he had already served his purpose. No harm in dying now.

"Merlin," Morgana said again insistently, and he glanced at her warily. "I won't tell."

The coldness from his missing magic slowed his surprise, but he managed a somewhat started blink. Morgana caught it, and frowned disapprovingly, regally offended.

"You can't truly think I'd repay your favor with betrayal," Morgana sniffed, and she consciously collected herself, recovering from her earlier shock. "When you realized my nightmares were prophetic, you risked your life to take me to the druids. It's only proper that I help you now. I helped Mordred, did I not?"

"Uther-" Merlin started, a twinge of unease creeping through him. This was too easy. His discovery was supposed to lead to accusations and death; he almost felt disappointed.

He didn't know if he felt disappointed because Morgana wasn't Arthur, or because he dreaded living without his magic and Morgana had abandoned the perfect excuse to end him.

"Uther is wrong," she said fiercely. She sat down next to Merlin's bed, ignoring Gaius's gaping. "Besides," she added hesitantly. "I'm glad to share this secret. I feel as if I've been going mad alone."

Merlin watched as she twisted her fingers together in her lap, although her face betrayed nothing. She'd grown better at hiding her emotions since the discovery of her magic, and in the end, her unreadable expression convinced him. He too would have gone mad without Gaius, and he suddenly felt a small amount of guilt break through his comfortable detachment. Explaining to Morgana the cause of her nightmares had eased his own conscious, but it had left her alone to deal with the ever-present threat of execution and isolation.

"Merlin," Gaius said tentatively, adjusting to the situation as well as he could in order to address the core of it. "What did you mean that your magic is gone?"

Merlin flinched. Morgana's eyes widened; she seemed to have missed the implications of their earlier conversation. She'd been too carried away with her first discovery.

"I traded it to save Arthur," he said dully. "The crystal said it could change destiny so that Mordred wouldn't kill him, if I gave up my magic."

"Mordred?" Morgana exclaimed.

"Merlin," Gaius said, going remarkably pale. "Destiny is not something to be trifled with."

"I couldn't change Morgana's visions," Merlin said. He wanted to go back to drifting. Living was so very tiring without magic. "I had to save him."

"Does Arthur know about your magic?" Morgana asked abruptly. Her eyes were bright, manic, hopeful, overwhelmed, alive.

Merlin thought that in comparison, his voice sounded so very dead. "No."

Morgana leaned back in response, her features morphing in confusion.

"Merlin, I know you're loyal to a fault, but why? I've been thinking lately," she said in a rush, as if she'd been longing to share, constantly rehearsing the phrasing, but had thought her words through so many times that they ran together. "Arthur will be king someday, and he kills our kind. I love him as a brother, but surely this makes him our enemy? We should distance ourselves now, so that later it hurts less when we must fight him to survive-"

"No," Merlin cut her off sharply. She snapped her mouth shut at the vehement refusal, watching him in surprise. "We can't blame him for Uther's mistakes, because Arthur is not his father. He can learn. When the time comes...He'll bring magic and justice back to Camelot. He will. I would trade my magic for him all over again, no matter how much it hurts now."

He realized he was crying. He felt more alive than he had since the trade; this was one thing he knew beyond any doubt. He'd dedicated his life and magic to it. He'd been willing to sacrifice both for it, and he had. Gaius watched with an odd expression on his face, and Morgana gazed at him silently, her mouth parted in astonishment.

"Well, I suppose someone will need to show him that not all magic is evil," she said eventually, pressing her lips together. "Even his thick skull won't win against the both of us."

She glanced at Gaius. "I apologize. Merlin needs rest, I'm sure. Is my potion ready?"

"Of course," he said, and he held out the forgotten flask mechanically. "I hope it helps, my Lady."

"I'm sure it will. Goodnight, Gaius," Morgana said with a cursory nod. "Merlin."

She straightened her hair, rising and slipping out the door, shutting it quietly behind her. Wasting no time, Gaius turned to him before her footsteps had even faded. Merlin had expected a scolding, but the physician's face held only a deep sadness.

"Oh, Merlin," he sighed, taking Morgana's chair and stroking back his hair. "You poor, brave boy. You have a good and foolish heart, and for that you suffer."

"It hurts, Gaius," he couldn't help but whisper, his throat tight. The emptiness threatened to choke him.

"I know, Merlin. I know."

ooo

Arthur knew something was odd. At first, he'd been so relieved by Merlin's return, he hadn't noticed, brushing off the strange behavior as leftover weakness from his illness. Merlin had been bedridden for nearly two weeks, and Arthur had missed him more than he would like to admit. Or would ever admit out loud, truth be told. George could bring perfect meals, clothes, and service, but Arthur felt that he needed someone with whom he could argue and throw things at more than he needed perfectly fluffed pillows.

Merlin was weak. The first few days he often stopped cleaning to catch his breath, whenever he thought Arthur wasn't watching. Except Arthur _was_ watching, and he saw that Merlin's arms trembled when they set down a tray of food and that fetching water for his bath took three times as long. He gave half-hearted criticism the first time, hoping that the teasing would snap Merlin out of his look of constant pain, but he received a flinch in response. Arthur didn't say anything again, but Merlin's shoulders hunched further and further as the days wore on.

Arthur tried asking nicely. For an entire week he gave shorter lists of chores than usual, didn't assign extra work when he finished too slow, and sent him to bed at a reasonable hour. Yet Merlin told him nothing. He knew he was a prince, but he'd always thought that-

No, he'd known that Merlin didn't tell him his problems. Sometimes his servant had quiet days, and while Arthur had always managed to coax him out of them before, he'd never learned what triggered them. He hated those days, because they reminded him that servants and princes couldn't be friends.

So when he turned the corner and ran into Merlin and Morgana, Arthur's jaw clenched.

"Merlin, if Arthur is being too hard on you-" she was saying, but Merlin shook his head.

"Arthur has been as considerate as he can be," Merlin said, and Arthur shifted, momentarily pacified. He'd known Merlin had noticed, but to have it said aloud made him feel warm, from embarrassment and something else he couldn't quite name.

"As considerate as he can be when he doesn't know," Morgana retorted.

Arthur tensed again; irritation flared as he realized that Morgana knew what ailed his servant when not only did he not know, but it was being kept from him deliberately. The dark, pervasive displeasure was familiar; Arthur recognized it from when he'd learned that Merlin had gone to Morgana about the crystal, not him.

"Gaius won't let me take any more time off," Merlin said tiredly. "He said I'd have to learn to live normally eventually, and it might as well be sooner rather than later."

Merlin was so _stupid_, Arthur raged, the words barely registering. He'd warned Merlin not to pursue his feelings for Morgana; he'd _told_ Merlin that Uther would have his head if discovered. Yet here they were, sharing and discussing secrets that Merlin refused to tell Arthur.

"Merlin," he interrupted sharply, stepping around the corner. "You should have told me that you had so much free time."

"Arthur," Morgana started warningly, but he didn't let her finish.

"I want you to polish my armour, clean out my room, re-feather my bed and pillows, clean the stables, and sharpen my sword. I expect it done by tomorrow morning."

It was a cruel demand, even by Arthur's standards, when dusk was already falling. To be perfectly fair, he'd fully expected Merlin to protest, and with the tactical advantage, Arthur had intended to trade the list of chores for the knowledge of why Merlin acted so distant.

Instead of a scathing retort, Merlin's shoulders slumped, and when he looked up, his gaze wouldn't focus on Arthur. They gazed blankly at some point over his shoulder, his features slack.

"Yes, my Lord," Merlin said in defeat, bending down to pick up the bucket of water he'd gone to fetch for Arthur's bath. A few drops sloshed out of the side and he was forced to use two arms for it, lifting the bucket unsteadily. "My Lady," he added, bowing his head to Morgana. He retreated quickly, perhaps to escape her growing wrath.

"Arthur," she hissed, in that voice she used just before she ranted.

"He's been neglecting his duties recently," Arthur defended weakly, still bewildered by Merlin's lack of response. He'd been quiet the past week, but somehow he'd thought Merlin would revive if he suffered a grave, avoidable injustice.

Morgana berated him plenty, but Arthur would have gone to find Merlin anyway.

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